U.S. patent application number 11/835117 was filed with the patent office on 2008-02-28 for turbomachine rotor blade.
This patent application is currently assigned to SNECMA. Invention is credited to Yvon CLOAREC.
Application Number | 20080050245 11/835117 |
Document ID | / |
Family ID | 37507783 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080050245 |
Kind Code |
A1 |
CLOAREC; Yvon |
February 28, 2008 |
TURBOMACHINE ROTOR BLADE
Abstract
A turbomachine rotor blade comprising a root (14) mounted in a
channel of the periphery of a disk and held by an annular flange
(18) which presses on the root (14) of the blade (12), this root
comprising a stop (44) engaging in a matching cavity of the flange
in order to stop it rotating about the axis of the disk, the
central portion of the stop having a thickness less than that of
the ends of the stop.
Inventors: |
CLOAREC; Yvon; (Ecuelles,
FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SNECMA
Paris
FR
|
Family ID: |
37507783 |
Appl. No.: |
11/835117 |
Filed: |
August 7, 2007 |
Current U.S.
Class: |
416/97R ;
416/204A; 416/220R; 416/223A |
Current CPC
Class: |
F01D 5/3015 20130101;
Y02T 50/60 20130101; Y02T 50/671 20130101 |
Class at
Publication: |
416/97.R ;
416/204.A; 416/220.R; 416/223.A |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2006 |
FR |
0607510 |
Claims
1. A turbomachine rotor blade comprising a root having a stop
formed in protrusion on one of its upstream and downstream end
faces, wherein the central portion of this stop has a thickness in
a direction substantially perpendicular to said end surface that is
less than that of the ends of the stop.
2. The blade as claimed in claim 1, wherein the central portion of
each stop is lightened by the removal of material.
3. The blade as claimed in claim 1 or 2, wherein the central
portion of each stop is removed by machining.
4. The blade as claimed in one of the preceding claims, wherein the
lightened or removed central portion of each stop has a length in a
direction substantially perpendicular to the longitudinal axis of
the blade and parallel to said end face that is at least equal to
approximately 3/4 or 4/5 of that of the stop.
5. The blade as claimed in one of claims 1 to 4, wherein its root
has a dovetail or dogtooth shape in cross section.
6. The blade as claimed in one of claims 1 to 5, wherein the stop
is formed by machining or obtained by casting.
7. A turbomachine rotor disk, comprising blades as claimed in one
of the preceding claims whose roots are mounted in channels of the
periphery of the disk, and an annular flange that is mounted
coaxially on the disk and that presses on the roots of the blades,
the stop of each blade root being engaged in a matching cavity of
the flange in order to stop it rotating about the axis of the
disk.
8. A turbomachine which comprises at least one rotor disk as
claimed in claim 7.
Description
[0001] The present invention relates to a rotor blade, in
particular for a compressor of a turbomachine such as an aircraft
turbojet or turboprop.
BACKGROUND OF THE INVENTION
[0002] The blades of a compressor stage comprise roots engaged in
axial channels of the periphery of a rotor disk and held by an
annular flange formed of several sectors that is mounted via an
external annular rim in an internal annular groove of the
downstream face of the disk. This flange presses axially at its
radially external end on the downstream ends of the blade roots,
and at its radially internal end on the downstream face of the disk
by means of an annular sealing snap-ring.
[0003] The internal annular rim of the groove of the disk and the
annular rim of the flange are scalloped or crenellated in a
matching manner, which makes it possible to bring the flange inside
the annular groove of the disk by axial translation when the solid
portions of the scalloped rim of the flange are in line with the
hollow portions of the scalloped rim of the annular groove. The
flange is then axially locked by rotation in the annular groove of
the disk until the solid portions of the scalloped rim of the
flange are in line with the solid portions of the scalloped rim of
the annular groove of the disk and are axially pressing on the
latter.
[0004] The blades comprise stops that are formed on downstream
faces of their roots and that are designed to be engaged with a
slight circumferential clearance between adjacent solid portions of
the annular rim of the flange in order to stop the flange rotating
in the annular groove of the disk. Each stop has an elongated shape
in the circumferential direction and extends from one lateral edge
to the other of the downstream face of the blade root, the lateral
ends of the stop interacting by abutment with the adjacent solid
portions of the scalloped rim of the flange in order to stop it
rotating. This stop is formed by a large volume of material which
significantly adds weight to the blade and hence the rotor
disk.
DESCRIPTION OF THE PRIOR ART
[0005] It has already been proposed to reduce the weight of the
rotor blades by reducing the length of their stops in the
circumferential direction. However, this solution is not
satisfactory because it makes it necessary in consequence to modify
the scalloped rim of the flange, by increasing the circumferential
extent of the solid portions of its rim, in order to retain the
aforementioned slight circumferential clearance between the stops
and the solid portions of the rim of the flange, which also leads
to an increase in the weight of the flange and hence of the rotor
disk.
SUMMARY OF THE INVENTION
[0006] The object of the present invention is in particular to
provide a simple, effective and economic solution to these
problems.
[0007] Accordingly it proposes a turbomachine rotor blade
comprising a root having a stop formed in protrusion on one of its
upstream and downstream end faces, wherein the central portion of
this stop has a thickness in a direction substantially
perpendicular to said end surface that is less than that of the
ends of the stop.
[0008] The ends of the stop have a thickness determined by their
function of abutment on solid portions of the rim of the flange,
and the central portion of this stop may have a much lesser
thickness, even zero, without adversely affecting the stopping of
rotation of the flange.
[0009] The invention therefore makes it possible to reduce the
weight of the rotor blades without, for all that, modifying the
scalloped rim of the flange because the circumferential distance
between the lateral ends of the stops remains unchanged.
[0010] The slight thickness of the central portion of the stop also
has no effect on the seal of the assembly because this seal is
provided by the radially external portion of the flange pressing on
the blade roots and by an annular snap-ring mounted between the
radially internal portion of the flange and the disk.
[0011] The central portion of each stop may be lightened by the
removal of material. Preferably, it is removed by machining. This
central portion has, for example, a length in a direction
substantially perpendicular to the longitudinal axis of the blade
and parallel to said end face that is at least equal to
approximately 3/4 or 4/5 of the length of the stop.
[0012] The root of the blade has, for example, a dovetail or
dogtooth shape in cross section. The stop of the blade may be
formed by machining or obtained by casting. As a variant, it may be
fitted and attached by welding, riveting, screwing, bonding, etc.,
onto the blade root.
[0013] The invention also relates to a turbomachine rotor disk
comprising blades as described above whose roots are mounted in
channels of the periphery of the disk and an annular flange that is
mounted coaxially on the disk and that presses on the roots of the
blades, the stop of each blade root being engaged in a matching
cavity of the flange in order to stop it rotating about the axis of
the disk.
[0014] The invention also relates to a turbomachine, such as an
aircraft turbojet or turboprop, which comprises at least one rotor
disk as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Other advantages and features of the invention will appear
on reading the following description made as a nonlimiting example
and with reference to the appended drawings in which:
[0016] FIG. 1 is a partial schematic view in axial section of a
turbomachine rotor disk;
[0017] FIG. 2 is a schematic half-view in axial section of the
annular flange of the rotor disk of FIG. 1, on a larger scale;
[0018] FIG. 3 is a partial schematic view in perspective of the
rotor disk of FIG. 1, seen from downstream;
[0019] FIG. 4 is a partial schematic view in perspective of the
root of a blade of the rotor disk of FIG. 1, seen from
downstream;
[0020] FIG. 5 is a partial schematic view in perspective of the
root of a blade of a rotor disk according to the invention, seen
from downstream.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Reference is made first to FIGS. 1 to 4 which illustrate the
technique involved in the present invention.
[0022] The rotor of a turbomachine compressor comprises a plurality
of rotor disks, one of which is shown partially in FIGS. 1 and 3,
each disk 10 supporting a plurality of substantially radial blades
12 whose roots 14 are engaged in axial channels 16 of the periphery
of the disk 10.
[0023] The roots 14 of the blades are retained radially in the
channels 16 of the disk by interaction of shapes, these channels 16
being for example dovetailed as shown in FIG. 3. The blades 12 are
immobilized axially in the channels 16 by an annular flange 18
mounted on the downstream face of the disk 10 and by a locking ring
20 mounted on the upstream face of the disk.
[0024] The locking ring 20 is split and is radially compressed in
order to be inserted into an annular groove 22 opening radially
toward the inside of the upstream face of the disk 10. This ring 20
presses axially on the upstream ends of the roots 14 of the blades
of the disk 10, thereby ensuring that they are axially retained in
the upstream direction.
[0025] The annular flange 18, more visible in FIG. 2, is formed of
angular sectors, for example five in number, and comprises upstream
an annular rim 24 oriented radially toward the outside and housed
in an annular groove 26 opening radially toward the inside of the
downstream face of the disk 10. The annular rim 24 of the flange is
scalloped or crenellated, that is to say that it has solid portions
28 formed alternately with hollow portions 30 evenly distributed
about the axis of the flange.
[0026] The radially external portion 32 of the flange 18 presses
axially on the downstream ends of the roots 14 of the blades of the
disk 10, thereby ensuring that they are retained axially in the
downstream direction.
[0027] The annular flange 18 comprises, in its radially internal
portion 34, an annular groove 36 opening axially upstream for the
housing of an annular sealing snap-ring 38 designed to be clamped
axially between the downstream face of the disk and the bottom of
the groove 36 and to be deformed radially outward in operation
under the effect of the centrifugal forces.
[0028] The internal annular rim 40 of the groove 26 of the disk is
scalloped or crenellated like the annular rim 24 of the flange 18,
which makes it possible to engage the rim 24 of the flange 18 in
the groove 26 of the disk by axial translation, when the solid
portions 28 of the rim of the flange are in line with the hollow
portions of the rim 40 of the groove 26. The flange 18 is then
immobilized axially by rotation in the groove 26 of the disk until
the solid portions 28 of the rim 24 of the flange are in line with
the solid portions 42 of the rim 40 of the groove and pressing
axially on these solid portions.
[0029] The downstream flange 18 is prevented from rotating about
the axis of the disk 10 by means of stops 44 formed on the
downstream ends of the roots 14 of the blades and designed to nest
with a slight circumferential clearance in the hollow portions 30
of the annular rim 24 of the flange 18 (FIGS. 1 and 4).
[0030] In a known embodiment, the stop 44 of each blade 12 is
formed in protrusion on a downstream radial face 46 of the blade
root 14 and has a parallelepipedal shape that is elongated in the
circumferential direction and extends from one lateral edge to the
other of the downstream face 46 of the root.
[0031] The stop 44 comprises a substantially radial downstream face
48 that is connected to the lateral faces 50 of the blade root 14
by faces 52, 53 designed to come into abutment in the
circumferential direction on adjacent solid portions of the annular
rim 24 of the flange in order to stop it rotating in the groove 26
of the disk. The faces 52, 53 may be in line with the lateral faces
50 of the blade root. The face 52 of the stop, situated on the
right in the drawing, is designed to come into abutment on a solid
portion 28 of the scalloped rim of the flange in order to stop the
flange 18 rotating in one direction of rotation (arrow 54--to the
left in the drawing) about the axis of the disk, and its face 53,
situated on the left in the drawing, is designed to come into
abutment on an adjacent solid portion 28 of the rim of the flange
in order to stop it rotating in the opposite direction of rotation
(arrow 56--to the right in the drawing) about the axis of the
disk.
[0032] The invention makes it possible to lighten this type of
blade thanks to a lesser thickness of the central portion of the
stop. The "thickness" of the stop means the dimension of the stop
in a direction parallel to the axis of the disk. The central
portion of the stop has a slight or even zero thickness and the
lateral ends of the stop that comprise the aforementioned abutment
faces have a thickness that is substantially identical to that of
the stop of the prior art.
[0033] In the exemplary embodiment of the invention shown in FIG.
5, the central portion of the stop 144 has been removed by
machining, the lateral ends of the stop 144 being substantially
identical and independent and at a circumferential distance from
one another.
[0034] Each end of the stop 144 comprises a substantially radial
downstream face 148 connected to the lateral face 150 of the
nearest blade root via an abutment face 152, 153. The abutment face
152 of the stop 144, situated on the right in the drawing, makes it
possible to lock the flange in the direction of rotation 154 about
the axis of the disk, and the abutment face 153 of the stop 144,
situated on the left in the drawing, makes it possible to lock the
flange in the direction of rotation 156 about the axis of the
disk.
[0035] The length and width of the stop according to the invention
are substantially identical to those of the stop of the prior art.
The "length" of the stop means the dimension of the stop in a
circumferential direction relative to the axis of the disk, and the
"width" of the stop means the dimension of the stop in a radial
direction relative to this axis. The length of the central portion
of the stop 144 is determined partly in order to significantly
reduce the weight of the blade 12 and partly so that the ends of
the stop retain a sufficient mechanical strength so as not to be
damaged by butting against solid portions of the scalloped rim of
the flange. Typically, the lightened or removed central portion of
each stop has a length at least equal to approximately 3/4 or 4/5
of the length of the stop.
[0036] The rotor disk according to the invention is assembled in
the following manner:
[0037] The sectors of the flange 18 are mounted one after the other
onto the downstream face of the disk 10 by axially aligning the
solid portions 28 of the scalloped rim of the flange with the
hollow portions of the scalloped rim 40 of the disk and by moving
the sectors toward the disk, in a direction parallel to the axis of
rotation of the disk, until the annular rim 24 of the flange is
engaged in the groove 26 of the disk.
[0038] The sectors of the flange are then moved in rotation in the
groove of the disk until the solid portions 28 of the annular rim
of the flange are axially in line with the solid portions 42 of the
rim of the groove 26 of the disk in order to axially immobilize the
flange on the disk.
[0039] The blades 12 are mounted one after the other onto the disk
by axially engaging their roots 14 from upstream in the channels 16
of the periphery of the disk, until the stops 144 of the blades are
engaged in the hollow portions 30 of the scalloped rim of the
flange and these stops are in line transversely with the solid
portions 28 of the scalloped rim of the flange. The ring 20 is then
compressed radially and engaged in the annular groove 22 of the
upstream face of the disk in order to axially lock the blades 12
onto the disk.
[0040] The stop 144 according to the invention may be obtained by
machining the root of a blade according to the prior art. For this,
an appropriate tool is moved one or more times in a direction 160
substantially parallel to the longitudinal axis A of the blade on
the central portion of the stop 144 in order to remove material by
machining. The central portion of the stop may also be removed by
ECM (Electrochemical Machining) or EDM (Electrical Discharge
Machining).
[0041] As a variant, the stop 144 may be cast with the blade 12 or
be fitted and attached to the blade root.
* * * * *